Calendar timepiece with month advancement mechanism for 29,30,or 31 day months

ABSTRACT

A calendar watch comprising a date calendar display dial, a month calendar display dial and a date feed wheel, all being rotatably mounted on the movement of said watch, said wheel being driven by said movement for performing a complete revolution per 24 hours, said watch being characterized by that a spring-loaded pawl means for performing an automatic month end date feed operation to said date display dial is pivotably mounted on said wheel.

United States Patent Tsuzuki et al. July 4, 1972 1 1 CALENDAR TIMEPIECEWITH MONTH 2,286,000 6/1942 Neyhart ..58/5 ADVANCEMENT MECHANISM FOR 29,2,647,359 8/1953 Balzeau ..58/5 30, OR 31 DAY MONTHS 3,373,558 3/1968Makiri ..58/58 X [72] Inventors: Akira Tsuzuki; Choken Suzuki, both ofFOREIGN PATENTS 0R APPLICATIONS T k I 0 yo apan 1,575,397 6/1969 France..58/58 [73] Assignee: Citizen Watch Company Limited, Tokyo,

Japan Primary ExaminerRichard B. Wilkinson [22] Filed; June 11, 1971Assistant ExaminerGeorge H. Miller, Jr.

Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [21] Appl. No.: 1,521

ABSTRACT [30] Foreign Applicafion Priority Dan A calendar watchcomprising a date calendar display dial, a June 13, 1970 Japan ..4551251 month calendar p y dial and dam feed Wheel, being Dec. 24, 1970Japan ..45 1 18312 rotatably mounted on the movement of said watch, saidwheel being driven by said movement for performing a complete [52]U.S.Cl ..58/58,58/5 revolution per 24 hours, said watch beingcharacterized by [51 Int. Cl. ..G04b 19/24 that a spring-loaded pawlmeans for performing an automatic [58] Field olSearch ..58/4,5,6,58month end date feed operation to said date display dial is pivotablymounted on said wheel. [56] References Cited 1 Claim, 7 Drawing FiguresUNITED STATES PATENTS 1,997,511 4/1935 Canepa ..58/58 PATENTEU L 4m3.673.789 SHEET 30! 3 CALENDAR TIMEPIECE WITH MONTH ADVANCEMENTMECHANISM FOR 29, 30, OR 31 DAY MONTHS This invention relates toimprovements in andrelating to calendar timepieces. More specifically,it concerns with an improved calendar feed mechanism in a calendartimepiece.

The conventional calendar timepiece is generally so designed andarranged that its calendar feed mechanism comprises a date calendar dialrepresenting date symbols of a large month consisting of 31 successivedays and fed a date division per day when the timepiece movementoperates regularly. Therefore, it is necessary to correct the datecalendar dial manually at the end of every small month and February, soas to bring the first date symbol 1 visible through the transparent datewindow provided on the timepiece.

In order to obviate such frequently required troublesome calendarcorrections at month ends, various improved date calendar feedmechanisms have already been proposed. A representative and simplestmechanism of this kind comprises a lever pivotably mounted on the plateof the timepiece movement and adapted for being operationally controlledin its pivotal movement by certain cam means destined for performing thedescriminative operation between the larger months and smaller monthsincluding February. The pivotal movement of said lever for feeding thedate calendar dial is performed larger or lesser depending upon thelonger or shorter length of the months, respectively. Even in the abovekind simplest design of the date feed mechanism, the pivotable lever hascomparatively larger overall dimensions and requires further a largespace area for allowing the lever to oscillate in the required manner.In addition, there must be provided a relatively strong return springfor the pivotable lever which imposes a substantial counter torqueagainst the regular movement of the timepiece movement. In this priorproposal, said lever is arranged between the date feed wheel and thedate calendar dial so that a corresponding reduction in transmissionefficiency will be encountered in comparison with the common date feedmechanism wherein a direct drive is performed from the date feed wheelto the dial and thus no reliance is made upon the intermediatetransmission lever. It is highly difficult to fit the above kind offeeding lever in a modernized watch which must be miniatured as possibleand have a smallest overall thickness as possible. Especially, when aconcentrically arranged, ring-shaped date calendar dial is used with theabove kind mechanism of the prior proposal, the disadvantageous effectof the larger pivoting stroke of the lever will be still furtheraccentuated.

It should be noted that the term large month as used herein throughoutthe specification and appended claims means the regular odd calendarmonth which consists of thirty one successive days.

In the similar way, the term small month as used herein means theregular even calendar month which consists of thirty successive days.

A main object of the invention is to provide an improved date calendarfeed mechanism capable of obviating the troublesome calendar correctingoperation at each of the small months and providing an easy adaptabilityto a watch.

A further object is to provide the date calendar feed mechanism of theabove kind, capable of consuming a relatively small amount of energy forfeeding the date calendar dial.

Still further object is to provide the feed mechanism of the above kindrepresenting a relatively simple design and having only a small numberof constituent parts and being easy to manufacture and highly reliablein its operation.

These and further objects, features and advantages of the invention willbecome more apparent when read the following detailed description of theinvention by reference, to the accompanying drawings illustrative ofseveral preferred embodiments of the invention.

In the drawings:

FIG. 1 is a schematic and partial plan view of the date dial feedmechanism built in accordance with a first embodiment of the inventionwherein, however, the date dial is positioned to show the 30th day of alarge month and the regular time-indicating gear train and its relatedseveral working parts have been omitted from the drawing only forsimplicity.

FIG. 2 is a similar view to FIG. 1 wherein the dial is positioned at itstransient position from the 31st day of the large month to the 1st dayof a next succeeding month for showing the mode of dial feed at suchtransient period.

FIG. 3 is a similar view to FIG. 1 wherein, however, the dial ispositioned at its display position corresponding to the end of a smallmonth.

FIG. 4 is a similar view to FIG. 1 wherein, however, the dial ispositioned in its further display position corresponding to the finaldateof February.

FIG. 5 is a similar view to part of FIG. 1, illustrating, however, aslight modification of the first embodiment.

FIG. 6 is substantially similar view to FIG. 1, showing, however, asecond embodiment of the invention, wherein the date dial is positionedfor display of the 30th day of June.

FIG. 7 is a similar view to part of FIG. 6, wherein the related parts ofthe dial are positioned at their position when seen upon one tooth feedof date dial having been performed from the position shown in FIG. 6. I

Referring now to FIGS. 1-4, the first embodiment of the invention willbe described hereinbelow in detail.

Numeral 1 denotes a conventional plate of a watch movement, said platebeing shown only partially for simplicity. Although the plate 1 isformed with a number of milled recesses and drilled openings formounting several conventional parts as commonly known, these have alsobeen omitted from the drawing again for simplicity. Month star wheel 2has 12 peripheral teeth formed thereon and is rotatably mounted asconventionally on a conventional hour wheel. A month-discrimination cam3 is fixedly and concentrically mounted hour wheel 50, said cam beingformed on its periphery with five separated high portions 30 two ofwhich have each a doubled peripheral length than the remaining.Therefore, this means that there are in effect seven such high portionscorresponding seven large month: January, March, May, July, August,October and December, of a year round; four separate middle heightportions 3b corresponding to April, June, September and November; andfinally, a single lowest portion 30 corresponding to February.

Month display dial 4 shown only in chain-dotted line and carryingthereon l2 successive month display numerals of which only 2, 3 and 4are representatively shown and others have been omitted from the drawingfor simplicity, is concentrically and fixedly mounted on the cam 3. Asseen from the foregoing, these parts 2, 3 and 4 are arranged to berotatable in unison with each other. In this way, these parts 2, 3 and 4constitute in combination a rotatable month plate unit 5.

A springy jumper lever 6 is normally kept in pressure contact with theperiphery of said month star wheel 2, said jumper being fixedly mountedby its root portion, for instance, by means of set screws on the plate1, although it is shown only partially for convenience and the fixinglymounting means have been omitted from the drawing only for itspopularity and simplicity.

A ring-shaped date calendar dial 7, only partially shown forconvenience, is mounted rotatably on the plate 1 as conventionally,although the mounting means have been omitted from the drawing onaccount of their very popularity. This dial 7 carries thereon successive31 numerals: 1, 2, 30, 31 corresponding to 31 days contained in a largecalendar month, although only 29, 30 and 31 of which have been shown asrepresentative, said dial being formed with 31 inner teeth 7acorresponding to said 31 days.

One of these inner teeth 7a which corresponds to the numetal 30 anddenoted specifically with 7a-30, is formed with a projection 7b,preferably by a press job, and adapted for performing an automaticmonth-end feed of the date dial 7 by cooperation with a month feed lever15, as will become apparent as the description proceeds. Althoughnotshown, a jumper is pivotably mounted on the plate 1 so as to holdprovisionally the date dial 7 by pressure contact therewith, in thesimilar way of the foregoing jumper 6 relative to month star wheel 2.

Numeral 8 represents only schematically a conventional date feed wheelwhich is rotatably mounted on plate I by means of a stepped stud 51.This wheel 8 is kept in engagement with a member of the regular geartrain, not shown, of the watch movement and performs a completerevolution per 24 hours in clockwise direction as hinted by an arrow A".A first feed pawl 9 is fixedly and concentrically attached to the datefeed wheel 8, a second feed pawl 10 is being pivotably mounted on thesame wheel 8 around a pivot 8a rigid therewith. A wire spring 11 isprovided for urging the second feed pawl to turn counterclockwise. Forthis purpose, one end of the spring 11 is held in a retaining opening 80formed in the wheel 8, while the opposite end of the spring is held inposition by engagement with the tail part of the second pawl 10. And theactuating end at 9a of the first feed pawl 9 is adapted for drivingengagement with one of the teeth 7a of the dial 7, so as to feed it atooth pitch per 24 hours. On the other hand, pawl 10 is provided with adepending pin 10a which is positioned within the teritory of a circularopening 8b formed through the wheel 8, thereby the movable range ofsecond pawl 10 being properly limited.

Numeral l2 and 13 represent in phantom manner a monthand a date displaywindow formed on the conventional timeindicating dial plate, not shown,to the watch movement.

A month discriminator lever 14 formed into a bell crank lever ispivotably mounted on a pivot pin la studded on plate I, one arm of saidlever being kept in pressure engagement with the periphery of cam 3 andthe other arm being kept in pressure contact with second feed pawl 10for controlling the working mode of the latter, as will be describedmore fully hereinafter.

The discriminator lever 14 is so designed and dimensioned that when itsupper or motion-receiving arm is brought into contact with one of thehigh parts 3a of cam 3, the lever is urged to swivel clockwise and thelower or actuating arm of the lever will act upon second feed pawl 10 toswivel a certain degree in clockwise direction against spring force at11 thereby the pawl being receded from contact with the tooth 7a of datedial 7 as shown in FIG. 1.

On the contrary, when the motion-receiving arm of lever 14 is broughtinto contact with either of middle height portions 312 or lowerstportion 3c of cam 3, the lever 14 is swiveled counterclockwise from theposition shown in FIG. 1, the second feed pawl 10 being thereby broughtinto its operating position ready for engagement with the tooth 7a ondate dial 7.

A month feed lever 15 formed again into a bell crank lever, is mountedpivotably on a pivot lb which is studded on plate 1. On the lower oractuating arm of lever 15, there is provided an actuating pin 15a formedrigidly therewith and capable of engaging with said month-end feedingprojection 7b on the tooth 711-30. A stop pin 15b is further formedrigidly on lever 15 and receives the urging end of a spring 16 which isonly schematically and partially shown. The root end of this spring 16is fixedly attached onto the plate 1 by means of set screws, althoughnot shown. By the provision of these spring 16 and stop pin 15b, thelever 15 is held normally in position shown in FIG. 1.

With advancing rotation, shown by an arrow B, of date dial 7, the pin 7bthereon will be brought into engagement with the pin 15a on lever 15 sothat the latter is urged to swivel in clockwise direction from theposition shown in FIG. 1, thereby the month-feed star wheel 2 beingturned counterclockwise by such angle which corresponds to a calendarmonth. Upon disengagement of pin 7b from pin 15a, the spring force at 16will become effective again and the lever 15 will be returned back toits stable position shown in FIG. 1.

The operation of the first embodiment shown and described so far is asfollows:

When the watch movement, not shown, operates regularly, first date feedpawl 9 fixedly mounted on the date feed wheel 8 which is driven toperform a complete revolution per 24 hours will act upon date dial 7through on of its inner teeth 70 to advance the dial by a tooth pitchcorresponding to a calendar day for the alteration of the day displayvisible through the day window 13, when the calendar time does notcorresponds to a month's end and irrespective of the occasionalpositioning of second date feed pawl 10.

When it is now assumed that the calendar time is a certain date ofMarch, for instance, which is naturally a large month, themotion-receiving arm of discriminator lever 14 is kept in contact withone of high portions 3a on the cam 3, as shown in FIG. 1. With rotationof date feed wheel 8 under these operational conditions and as thesecond date feed pawl 10 comes at the proximity to date dial 7, the pawlis urged by discriminator lever 14, thereby the lower or actuating endof said pawl 10 receding from its working position towards the center ofwheel 8. Under these conditions, the actuating end of pawl 10 can not bebrought into engagement with the feed projection or pin 7b on thespecific tooth 7a-30, even at the end of the month of March. Therefore,in this case, first date feed pawl 9 alone operates to feed the dial 7tooth by tooth per day, as in the regular way as above mentioned.

In the transient period from the 3 1st day of the month to the first dayof the next succeeding month or April as shown in FIG. 2, the month-endfeeding projection 7b will act upon the month-feed lever'lS through itspin 15a and thus, the lever is swiveled clockwise, thereby star wheel 2being fed a tooth pitch corresponding to a month concurrently in thedirection shown by an arrow C". The star wheel 2 is held firmly inposition under the action of jumper lever 6, so as to display the numberof the next month or April through the viewing window l2. Discrirninatorcam 3 is also rotated concurrently and the month-discriminator lever 14is brought finally into contact with the specifically attributed one ofmiddle height portions 3b on the cam 3 to the calendar April. Thence,the projection 7b will pass over the pin 15a and month-feed lever 15 isreturningly brought into its stabilized off-service position under theinfluence of spring force at 16.

In the course of a small month such as April, the lever 14 is kept incontact with a specifically attributed one of middle height portions 3bon discriminator cam 3, as shown in FIG. 3. Therefore, the lower oractuating end of second date feed pawl 10 is shifted nearer towards thetoothed periphery of dial 8 than before. Under these conditions, whenthe projection 7b is brought to its position shown in FIG. 3 where thedate display of 30 on dial 7 is visible through date window 13, the pawl10 will act upon the projection 7b, so as to perform automatically amonth-end feeding operation. Thus, the dial 7 is fed a calendar day toshow now a further advanced date display of 3 l Next, first date feedpawl 9 acts upon the dial 7, so as to feed it still a further calendarday, thus the next succeeding date display of 1 of the next calendarmonth being visible at the window 13. Concurrently, and in the similarway as described above in the case of large month, month star wheel 2 isfed a tooth pitch under the action of month feed lever 15. Thediscriminator cam 3 rigid with star wheel 2 will be correspondinglyrotated, until discriminator lever 14 will have been brought intoengagement with a specifically attributed one of high portions 30 onsaid cam 3, to the next succeeding calendar month or May, in thispreferred example.

In the course of the smallest calendar month or February, discriminatorlever 14 is kept in contact with the sole lowest part 30 on cam 3 andthe pawl 10 is further swiveled counter clockwise from the foregoingposition under the influence of spring force at 11. At arrival of the29th day of February, the pawl 10 starts definitely to engage the pin 7band then feed the dial 7 successively two calendar days, so as todisplay of 31st day of the same month through the window 13. (See, FIG.4.) Then, the first date feed pawl 9 is brought into actuation to feedthe .dial 7 still a further calendar day so that the display 1"corresponding to the first calendar day of the next succeeding month orMarch is presented through the window 13 to a viewer. In the course ofthe transient period from the 31st to the 1st calendar display, monthdisplay dial 4 is also fed by a step corresponding to a calendar month.Therefore, the viewer can observe the next following month display 3which corresponds to the calendar month: March through display window12. Therefore, no manual calendar correction must be needed at the endof February of each leap-year. Such manual correction must be carriedout only at the end of February, if the year is of the common.

Under occasion, month star wheel 2 can be so modified that the toothvalleys formed between successive tooth projections thereof representthree difierent radii as measured from the center of the star wheel, asin the similar way to the specifically designed peripheral undulationsformed on the discriminator cam 3, the star wheel can perform theservice of the latter, in addition to its own month feed operation,although not specifically shown.

The first and second date feed pawls 9 and are so modified in theirdesign and arrangement to perform their dial feed operations in thereversed successive order from that employed in the foregoingembodiment, although not shown on account of easy occurrence to anyperson skilled in the art when he has read the foregoing description.

In addition, when necessary, the month display dial 4 can be dispensedwith by placing the month display symbols or numerals directly on thediscriminator cam.

In order to reduce the amount of energy consumed at every calendarcorrecting operation, the mechanism can be so modified that at the endof February two successive and automatic date dial feed steps areintroduced as at every small or even month in the foregoing embodiment.Or alternatively, the mechanism can be modified, only a single datecorrecting step is performed at the end of February, as performed at theend of every large or odd month in the foregoing embodiment.

In the modified arrangement shown in FIG. 5, the first date feed pawl at9 is fixedly mounted, as by welding or the like conventional fixingmeasure, on the second date feed pawl 10. As may be easily understoodfrom the foregoing description, the engaging degree between the tooth 7aand the first feed pawl 9' is not subjected to alteration practically inany way even with pivotal movement of the second feed pawl 10, thismodified first pawl 9 can perform the same operational function asbefore. Structural and operational features of other parts appearing inFIG. 5 are substantially same and thus denoted with same respectivereference numerals as before regardless of occasional minor differencein configuration.

Next, referring to FIGS. 6 and 7, second embodiment of the inventionwill now be described hereinbelow.

In this embodiment, numeral 101 represents the conventional plate of awatch movement and is shown partially and in a simplified form asbefore. A date feed wheel 102 is rotatably mounted on the plate 101 bymeans of a shaft 101a, preferably formed into a stepped screw, said feedwheel being adapted for performing a complete revolution per 24 hours inthe direction shown by an arrow B, since it is kept in cooperation witha certain proper member of the conventional time-keeping gear train, notshown, of the watch movement.

Date feed means comprising a pivotable date feed pawl 103 and an urgingwire spring 105 are mounted on thewheel 102, said pawl being pivotablearound a pivot pin 102a studded on the wheel. One end of said wirespring 105 is held in position by being received in a retaining hole102C formed in said wheel 102, while the opposite end of spring 105 iskept in engagement with the upper or idle arm of pawl 103 for urging thelatter to rotate in counter clockwise direction in FIG. 6. In this way,the pawl 103 is normally held in its contacting position with the shaft101a and occupies a most offset position in its counter clockwiseswiveling position as shown in FIG. 6. Although not specifically shown,the pawl 103 has a thickness enough for engagement with date calendardial 108 and month calendar dial 109.

A discriminator lever 106 is pivotable around a pin 1101b which isstudded on the plate 101, and formed with a projection 106b at anintermediate position between pivot pin l0lb and the free end 106a ofthe lever.

A wire spring 107 is provided which acts upon the lever 106 so as tourge the latter to swivel normally in counter clockwise direction. Inthis way, the spring 107 can act as a jumper for month calendar dial 109to be described more in detail. This spring 107 is kept in position bymeans of a pair of positioning pins 53 and 54 which are studded on theplate 101.

A ring-shaped conventional date calendar dial 108 is rotatably andconcentrically mounted on the plate 101 and carries thereon a series ofcalendar date display symbols l-3l of which only the symbol 30corresponding to the 30th day of a month is representatively shown. Thisdial 108 is formed with 31 inner teeth 108a corresponding respectivelyto the 31 date display symbols.

One of the inner teeth 108a which corresponds to the 31st calendar dayand is specifically demonstrated by attaching with a primed reference108a, has been designed to have a larger tooth height than others. Asseen, the tooth bottom 108a" defined between the high tooth 108a and anext following tooth l08a corresponding to the first day of the nextcalendar month is designed to have a lower bottom than others, said hightooth adapted for acting as a month-end feed projection as will becomemore apparent as the description proceeds.

Numeral 109 represents a month display dial acting howeversimultaneously as a month-discriminator cam, and carrying thereon twosuccessive series of month display symbols covering 24 successive monthsand is rotatably mounted on the plate 101 by means of conventional shaftand bearing means, not shown. The rotating center of the dial 109 ispositioned on a diameter which passes through the center of shaft 101aand the bearing center of date dial 108 and the month dial or cam ismounted eccentrically relative to the latter and the watch movement asseen from the drawing.

The month dial or cam 109 is formed with 24 successive inner teeth 109ahaving a tooth pitch substantially similar to that of those at 108a onthe date dial. As will become more apparent as the description proceeds,the tooth gaps of the teeth 109a is modified so as to provide themonth-discriminating cam function. More specifically, the bottom 109afor each of the teeth corresponding to the large or odd months has asmaller height as measured from the tooth top, and represents a shortertooth gap length than those at 109a" attributed to each of the teeth tothe small or even months, thereby providing a kind of discriminator cammeans.

The projection 106b on month discriminator lever can advance into thetooth gap 109a. In the even month, the lever projection is brought intoa deeper engaging position as shown in full line shown in FIG. 6, whilein the odd month, it will oc cupy its off-engagement position as shownin chain-dotted line in the same figure.

In the large or odd month, the lever end 106a will occupy a positionsituated within the actuating zone of the pawl end 103a when the pawl103 is positioned at its utmostly counterclockwise swiveled position. Onthe other hand, in the small or even month, the lever end 106a will bepositioned at its receded position from the actuating zone of pawl end103a.

Therefore, it will be seen from the foregoing that the month displaydial 109 can serve for the following three different functions:

1. month feed operation by its own in cooperation with pawl 103; 2.jumper action for its own and in cooporation with lever 1 06; 3.position control of month discriminator lever 106. For these purposes,the inner teeth 109a are designed to have different tooth gaps anddifferent tooth bottom heights as referred to above.

It should be noted at stage that both calendar display dials 108 and 109are so arranged that the dedendum circle, not

shown, of inner teeth 108a on the date dial 108 and the addendum circle109' of inner teeth 109a of month dial 109, having naturally differentradii of curvature from each other, overlap with each other at leastwithin the operational range of the date feed pawl 103 and that thecircle described by the tip end of the latter intersects each of saidaddendum and dedendum circles at two different points, although notshown, said points being positioned substantially in an overlapped waywhen seen relative to the both calendar dials on the drawing. It shouldbe further noted that between each pair of said intersection points, theaddendum circle establishes a tangential relationship to the dedendumcircle or occupies a slightly outer locus position outside the latter.In other words, the tip of each of inner teeth 109a can not be broughtto an inner position relative to the dedendum circle of inner teethbottoms, with exception of the specific tooth bottom 108a defined by andbetween the two successive teeth corresponding to the 31st and lst datedial displays.

Numeral 111 represents partially and imaginally a conventional daydisplay dial which is rotatably mounted on the conventional hour wheel,not shown, of the watch movement, said dial 111 being positioned at ahigher level than the month display dial 109 in FIG. 6 for avoidingotherwise invited operational interference. This dial 1 11 is fed a stepin the direction shown by an arrow A under influence of the regulartimekeeping operation of the watch movement through conventionaltransmitting mechanism, not shown, at the end of each day. Numeral 112,113 and 114 represent schematically the respective viewing windows forthe date-, monthand day calendar displays, respectively.

The operation of the second embodiment so far shown and described is asfollows:

The date feed wheel 103 performs a complete revolution per 24 hoursunder the influence of regular operation of the time-keeping gear train,not shown, of the watch movement.

In an even month such as June, a day display symbol J UN will be visiblethrough the window 1 13 as shown in FIG. 6. The projection 106b ofdiscriminator lever 106 will advance in this case into the tooth spacepartially defined by the deeper tooth bottom 109a", thus operatable inits small month display operation.

In every day of the month except the end thereof, the date feed pawl 103rotating in the direction B shown in FIG. 6, will be brought intoengagement with a specific one of the inner teeth 108a which correspondsto that positioned in close proximity to a specific point denoted a", soas to feed the date dial 108 by a single step in the direction shown byarrow C and corresponding to a calendar day for 24 hours, and the thusfed position of dial 108 is provisionally held by the spring pressureexerted thereupon by the conventional jumper lever, not shown. This datecalendar feed operation will be successively executed at every end ofthe successively following days in the similar way as above. In thisway, the thus fed successive date displays will appear through thewindow 112. Since there is a specific geometrical relationship betweenthe dedendum circle of the inner teeth 108a and the adendum circle ofthose at 109a as above described, the pawl 103 can not engage in thiscase with the inner teeth 109a and thus, no feed of the month displaydial is not performed at all.

Nearly at the end of the 30th day of June, the high tooth 108a ispositioned at a tooth pitch distance in advance of the said point a", asshown by c. At this stage, the day calendar display 30" is visible atthe window 112. It will be seen from the foregoing that the tip end 103aof date feed pawl 103 at this stage will be brought into engagement withhigh tooth 1080, so as to feed the dial 108 while sliding along therelated tooth flank towards the tooth bottom 108a". When the pawl end103a occupies the position in close proximity to said point a as shownin FIG. 7, it will then engage additionally with the related one of theteeth 109a, thereby both dateand month dials being fed each a respectivestep. In effect, the date dial has thus been fed by 2 calendar days andthe month dial has been fed by 1 month.

Then, the pawl 103 will disengage from contact with the related innertooth 109a and the high tooth 1080', but the month dial 109 is heldresiliently in position by pressure contact with the discriminator lever106 and the date dial 108 by the jumper lever, not shown. Through themonth window 113, the display: JUL will now be seen; and through thedate window 112, the numeral l corresponding to the first day of themonth may now be observed by the viewer, respectively. In the dialfeeding period at the end of this even month: July, even when the pawlend 103a should engage specific one of the inner teeth 109a which is nowpositioned at the point 0", it will contact only the related tooth topand slide therealong, thus performing no dial feed. In the course of asmall month and even when one of the teeth 1080 except the high tooth108a occupies the closest position to a point c, the date feed pawl end103a will only slide along the related tooth top; thus no feed of datedial 108 being invited in this case.

When, as an example, the calendar displays show the date of July lstupon execution of a calendar feed at the end of a small month, such asJune as was above referred to, then the lever projection 106b willinvade into the tooth gap corresponding to the shallow tooth bottom109a. Thus, the month discriminator lever 106 will occupy itschain-dotted line position corresponding to the large month from itsfull line one corresponding to the small month as shown in FIG. 6, uponmaking a clockwise swivel motion. Therefore, the actuating end 106a oflever 106 will invade into the operational zone of pawl 103 when itoccupies its utmost counterclockwise rotated offset position.

At the end of each date, the date dial 108 is fed a step through thefeed engagement of one of the inner teeth 108a which occupies theposition a as in the similar way to the case of large month as abovereferred to.

Since the discriminator lever 106 occupies the chain-dotted lineposition in the case of a large month such as July, as was referred toabove, and when assuming that the high tooth 1080' will be brought tothe position close to the point c at the 30th day of the month, the pawl103 will perform a clockwise turning movement by the action of the lever106 through its actuating end 106a and thus can not be brought intocooperation with the high tooth now occupying its position closest tothe point c. Therefore, the date feed pawl 103 can cooperate with thetooth 108a which is situated at the point a. Thus, the date display atthe window 112 will be "31" and the high tooth 108a will be brought tothe point a.

Next, at the end of the 31st date of the month, date feed pawl end 103awill invade into the tooth gap corresponding to the deep tooth bottom108a on date dial 108, thus the high tooth 108a occupying the positionat a and the related one of inner teeth 109a are subjected to respectiveone step feed. Therefore, the calendar displays will be AUG. 1" and thediscriminator lever 106 will engage the shallow tooth bottom 109a.

In the present second embodiment, the drive of month display dial 109 isperformed directly through the date feed wheel, thus minimizing thetransmission energy lost appearing in this respect. The number of themain operating constituents of the mechanism is also minimized by thefact that there are only the date dial, the month dial, the date feedwheel and the month discriminator lever and the whole mechanism is ofutmost simple design. Therefore, the dateand month calendar displaysymbols can be designed to relatively large dimensions. Even if themechanism should be made smaller, it is In the second embodiment, thedepths of the inner teeth of month dial 109 can be designed so as to beuniform overall when the depth is properly large, by only varyingsuitably the tooth gaps of these teeth, as will be seen from theforegoing detailed description of the second embodiment.

In either of both embodiments shown, the conventional quick feed meanscan be embodied in the mechanism so far as the feed period of the datedial by the date feed wheel, for the purpose of shortening substantiallythe date correcting period of the mechanism.

The embodiments of the invention in which an exclusive property orprivilege is claimed are as follows:

1'. A calendar feed mechanism for a watch movement, comprising incombination of:

a date calendar display dial rotatably mounted on said watch movement;

a series of 3 1 date calendar symbols carried on said dial;

a series of feeding teeth formed on said dial and in correspondence tosaid date calendar symbols;

a month end feed projection formed on said dial;

a month calendar display dial rotatably mounted on said movement, saidmonth dial being adapted for making partial rotation of a step for acomplete revolution of said date dial;

a series of month calendar symbols covering at least a year and carriedon said month dial;

a month discriminator cam made integral therewith;

a date feed wheel for making a complete revolution for 24 hours by beingdriven by said movement; and

a day feed pawl means pivotably mounted on said date feed wheel;

said day feed pawl means being controlled by said discriminator cam andadapted for advancing said date dial daily by a date calendar step andengaging said projection at each end of a 29, 30, or 31 day month toadvance the month calendar display dial.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,673, 789 Dated July 4, 1972 Inventons Akira TSUZUKI and Choken SUZUKI Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

IrT the Heading:

The Application Serial No. is incorrect:

should read:

-Appl. No 152, 142

Signed andsealed this 17th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR

ROBERT GOTTSC'HALK Attesting Officer Commissioner of Patents ORM PC4050(10-69) USCOMM-DC 6O376-P69 u,s. GOVERNMENT PRINTING OFFICE: Iss9o-ass-au UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3, 673 789 Dated July 4, 1972 Inventor(s) Akira TSUZUKI and ChokenSUZUKI It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

In the Heading:

The Application Serial No. is incorrect:

should read:

-Appl. Nol: 152,142

Signed and sealed this 17th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

Commissioner of Patents F ORM PO-IOSO (10-69) USCOMM-DC 6D376-P69 u.S.GOVERNMENT PRINTING OFFICE I969 o-ass-su

1. A calendar feed mechanism for a watch movement, comprising incombination of: a date calendar display dial rotatably mounted on saidwatch movement; a series of 31 date calendar symbols carried on saiddial; a series of feeding teeth formed on said dial and incorrespondence to said date calendar symbols; a month end feedprojection formed on said dial; a month calendar display dial rotatablymounted on said movement, said month dial being adapted for makingpartial rotation of a step for a complete revolution of said date dial;a series of month calendar symbols covering at least a year and carriedon said month dial; a month discriminator cam made integral therewith; adate feed wheel for making a complete revolution for 24 hours by beingdriven by said movement; and a day feed pawl means pivotably mounted onsaid date feed wheel; said day feed pawl means being controlled by saiddiscriminator cam and adapted for advancing said date dial daily by adate calendar step and engaging said projection at each end of a 29, 30,or 31 day month to advance the month calendar display dial.